Lockstitch sewing machine



Och-22 1940. c. F. RUBEI. 2,218,556

` LOCKSTITCH SEWING MACHINE Filed Aug. 18, 1937 4 sheets-sheet 1 Us i,10 Flea 1 7 9 j 5 .9 15( Jg' 12 I g l f 5l -ZL P9 j 17 a 62 q 1151 Zi-.z

A 4 I @a MH@ .WL-"mk" 'A L l i 2112:; y J5 l' 151 I @L 5,5 f J0 @y I Q f,j W/TNEES INVENTOR- A TTORNE YS.

Oct. 22, 1940. C. F, RUBEL 2,218,556

LOCKSTITCH SEWING MACHINE Filed Aug. 18, 1957 4 Sheets-Sheet 2 y@ w75 erY WITNESSILS- 55 INVENTOR- 6. NL. ,52 charm :v1/mimi,

M BY m m ATTORNEYS.

Oct. 22, 1940. c. F. RUBEL 2,218,556

LOCKS TITCH SEWING MACHINE Filed Aug. 1B, 1937 4 Sheets-Sheet 3 I N VENTOR:

E Charlas Rubl/ y 4 BY @t Q A T'I'ORNE YS.

OL 22, 1940. C, F, RUBEL 2,218,556

LOCKSTITCH SEWING MACHINE Filed Aug 18. i937 4 Sheets-Sheet 4 W1TNESSES-- ,55 INVENTOR;

(fg 5f j I Charles fuiml,

@wl/mfg AT'/ URNEYS.

Patented Oct. 22, 1940 g Locxs'rrrcn SEWING-MACHINE Charles F. Rubel,Chicago, Ill., assigner to Union j Special Machine Company, Chicago,Ill., a. corporation of Illinois Application `August 1s, 1937, serialNo. 159,645

7 Claims.

This invention relates to sewing machines of the type wherein acomplemental rotary stitchforming means cooperates with the needle inthe l .production of lwhat are known as lockstitch seams. Suchcomplemental stitch forming means usually consists of an axially hollowhook component, a non-rotating frontally open hollow bobbin case holderwhich occupies the hollow of the hook component, 'and a removable bobbin10 case with a needle clearing opening at its top which in turn occupiesthe hollow of the holder and accommodates a bobbin within it.. Indescending, the needle passes in closeproximity to thefront of therotary hook member, and in the eventthat it is bent or deflected bYmacross seam or other thickness irregularity in `the material being sewed,itv invariably enters the open front of the bobbin case holder throughthe needle clearing opening in the top of the bobbin case and fouls thebobbin within said case, thereby either scoring or otherwise damagingthe bobbin to the extent of rendering it unsuitable for further use, orbeing itself broken by impact with 35 A further aim of my invention isto attain the foregoing advantages without interfering with the normalfunctioning of either the complemental stitch-forming means or theneedle, which desideratum I also attain as hereinafter set forth 40through formation of the guard as a forward cam projection, of therotary hook member which during rotations of the latter passestransversely of the path ofthe needle as the latter descends withoutcontacting it except in the event of the 45 contingencies noted.

Other objects and attendant advantages will appear `from the followingdetailed description of the attached drawings, wherein Fig. I is afragmentary view, in plan, of a lockstitch sewing machine convenientlyembodying my invention, a portion of its work support having been cutaway forv exposure of important underlying elements of the machinemechanism.

55 Fig. II is a' staggered cross-sectional view of the machine taken asindicated by the arrows II-II in Fig. I.

Fig. III is a fragmentary sectional view axially through thecomplemental stitch-forming means which cooperates with the needle inproducing 5 the lockstitch seams, the section being taken as indicatedbythe arrows III-III in Figs. I and II and drawn to a largerscale.

Fig. IV is a detail sectional view taken as indicated by the arrowsIV-IV in Fig. III. 1o

Figs. V and VI' are views corresponding respectively to Figs. III andIV, but with the rotary hook element of the complcmental stitch-formingmeans and the needle in a diierent position.

Figs. VII and VIII are, in turn, views like Figs. l5 V and VI` with therotary hook element o f the complemental stitch-forming means and theneedle in still another position; and

.Y Fig. IX is a perspective view of a gib associated with the rotatingmember` of the complemental 20 stitch-forming means which constitutesthe needle guarding means of my present invention.

The lockstitch sewing machine herein illustrated is identical inconstruction with that of my copending application Serial Number159,646, concurrently filed herewith, its horizontal work support ,Ihaving a removable throat plate 2 with an opening 3 ltherein throughwhich a feed dog 4 operates upwardly to intermittently advance thematerial (not shown) being sewed on said work support. A presser foot 5pivotally connected at 6 to a shank 1 at the bottom of a presser bar 8,serves, as ordinarily, to hold the material down on the work support.'I'he needle 9 of the machine is carried at the lower end of avertically reciprocating bar I0 above the work support I which isactuated by suitable mechanism (not shown) so that said needle is movedup and down through the throat plate 2 to Vcooperate with acomplementalA rotary stitch-forming 40 means generally designated by thenumeral II.

The feed dog 4 of the machine is mounted on the top of a cantilever I2which overreaches the complemental stitch-formingv means II` and whichhas a vertically-slotted pendant shank I3 secured by a clamping screw I4to the front end of a feed bar I5. By virtue of this construction, thefeed dog 4 can be adjusted vertically relative to the feed bar I5 inadapting the machine for operation on materials of differentthicknesses. At its rear end the feed bar I5 has a pivotal connection I6with a rocker I1 on a, rock shaft I8 whereof the opposite ends areengaged kin downwardly-projecting bearing lugsy I9, 20 of the worksupport I. Up and down or lift movements are or feed movements from theshaft 2| through means including an eccentric 21 on said shaft with astrap 28 whereof the rod 29 is composed of two telescopicallyinterengaging components 29a, 29h, the component 29h being pivotallyconnected at 38 to the rocker I1 as shown in Fig. II. By means of a lazybar 3I pivotally connected at 32 to the component 28h of the strap rod23, said component is coupled with an arm 33 on alongitudinally-extending regulating shaft 36 also suitably ;lournaledbeneath the work support I. By rotatively adjusting the regulating shaft35, it is possible to vary the throw of the feed dog 4, and in turn thestitch length as may be desired or required.

The complemental Stich-forming means I I comprises a rotary hook mem'ber36 with a needle loop-engaging beak 31 and a loop-releasing tail 38; abobbin case holder 39 which fits into the hollow of the Irotary hook;and a case 40 for a bobbin 4I which in turn fits into the hollow of thebobbin case holder and which is provided with a needle clearing opening42 at the top. As usual, the rotary hook member 36 is formed at the backwith an axial boss 43 and secured by means of screws 44 to the front endof a shaft 45 which is parallel with the shaft 2| and journaled in abearing 46 intergrally formed with the bearing 22. By a suitabletransmission mechanism (not illustrated), the rotary hook member 36 isrotated twice during each feeding traverse of the feed dog 4 and eachvertical reciprocation of the needle 9. Moreover, as usual, the faceflange 41 of the bobbin case holder 39 is formed at the top with a notch48.for engagement by a rearward projection 49 on a rotation-restrainingnger 50 secured by screws I to the underface of the work support I. Asshown in Fig. I, sufficient clearance is allowed between the projection49 of the rotation-restraining finger 50 and the notch 48 of the flange41 on the bobbin case holder 39 to permit free reeving of the needlethread (not illustrated) during the formation of the lockstitches in thewell known way. As in my copending application, and as shown in Figs.III and VI, the circumferential rib 52 on the bobbin case holder 39 isconsiderably narrower than the internal receiving groove 53 of therotary hook member '36 so that normally said bobbin case holder is freeto oat axially. At 54 is indicated a steadying element in the form of atriarm whereof the cylindric shank 55 is secured by means of a set screw56 in a boss 51 at the end of an arm 58 pivoted for horizontal movementto the screw stud 59 surrounded by a helical spring 60 engaging upwardlyinto the feed bar I5. 'Ihe arm 58 is held in the position shown in Fig.I by a latch hook 6I, pivotally connected at 62, to one side of thependant projection 26 of the feed bar and urged upwardly by a spring 63.

By depressing the latch 6I, the arm 58 and the steadying element 54carried thereby will be swung outward away from the rotary hook member36 as far as permitted by a stop 64 on the feed bar I6 by the helicalspring 60, so that access may be had to the bobbin case holder 39 wheninterchange of bobbins is necessary. The operation and function of thesteadying .member 64 is fully described in the copending applicationhereinbeiore referred to and need not therefore be further dealt withherein.

The guard which I have provided to prevent the needle 9 from fouling thebobbin 4I of the complemental stitch-forming means II in the event thatit is deflected or bent by cross seams or other thickness irregularitiesin the material being sewed in the machinel is in the form of aforwardly projecting edge cam 66 on a segmental plate gib 61 lyingradially beyond the loop engaging beak 31. said gib providing theloop-releasing tail 38 and being detachably secured to the peripheryofthe rotary hook member 36 by three screws 68, see Figs. I and IX. Asshown, the cam projection 66 has a straight fiat surface 69 centrallybetween oppositely inclined flanking approaches and 1I.

The operation of my improved sewing machine is as follows: During eachrotation of the hook member 36, the approach 10 of the guard camprojection 66 reaches the path of the needle 9 at just about the timewhen said needle has `descended to the level oi' the top of said hookmember as shown in Figs. III and IV. With continued rotation of the hookmember 36 and further'descent of the needle 9, the straight porl tion 69of the guard cam 66 crosses the path of the needle slightly to the rearof the latter as shown in Figs. V and VI so that it does not normallycontact with the needle. However, should the needle be bent or deflectedinwardly toward the hook member 36 during this portion of the rotativecycle of the latter, it will be urged outwardly gradually by theinclined approach 10 of the cam projection 66 before it approaches therange of the loop engaging beak 31. The needle is Aaccordingly preventedfrom entering the open front of the bobbin case holder 39 through theneedle clearing opening 42 in the bobbin case 40, and from fouling thebobbin 4I as it continues in its descent to its lowest position (Figs.VII and VIII) by which time the flat portion 69 of the cam has passedfrom behind it. It is to be particularly noted from'Figs. V and VI, thatthe portion 69 of theguard passes behind the needle 9 at a time when thebobbin case holder 39 is free to float axially.

It will thus be apparent from the foregoing, that I have provided asimple and efficient means for preventing injury to the complementalstitchforming mechanism of a lockstitch sewing machine by a bent ordeflected needle as well as for protecting the needle against breakage.While I have illustrated and described my invention for convenience inassociation with a special and improved form of complemental rotarylockstitchforming means, it will be evident that the same can beembodied with attainment of advantages equal in all respects to thosehereinbefore pointed out, in complemental lockstitch-forming means ofordinary construction without departing from the scope of my inventionas defined in the appended claims. Y

Having thus described my invention, I claim:

1. In a lockstitch sewing machine, reciprocating needle; cooperativecomplemental stitchforming means with its axis at right angles to theneedle including an axially-hollow rotary hook member with a needle loopengaging beak, a frontally-open non-rotating bobbin case holder withinthe hollow of the rotary hook member, a

bobbin case with a needle clearing opening in its top removable fromsaid holder, and a bobbin within the bobbin case; and a guard movablewith the complemental stitch-forming means for engaging the needle, inthe event that the latter is bent or deflected, before it reaches thepath of the loop seizing beak of the rotary hook member and preventingsaid needle from fouling the bobbin within the bobbin case.

2. In a lockstitch sewing machine, vertically reciprocating needle;cooperative complemental stitch-forming means including ahorizontallyarranged hollow rotary hook component with a needle loopengaging beak; a frontally open nonrotating bobbin case holder withinthe hollow of the rotary hook component, a removable bobbin case ttingwithin said bobbin case holder and having a needle clearing opening inits t?, and a bobbin within said bobbin-case; and 'a needle guard in theform oi' a forwardly projecting cam edge at the periphery of the rotaryhook for engaging the needle, in the event that it is bent or deflectedas it descends, before it moves into the path of the needle loopengaging hook to prevent it from fouling the bobbin within the bobbincase.

3. In a lockstitch sewing machine, a vertically reciprocating needle;cooperative complementa] stitch-forming means including `ahorizontallyarranged axially hollow rotary hook member with a needleloop engaging beak, a frontally open nonrotating bobbin case holderwithin the hollow of the rotary hook member, a bobbin case fittingwithin said -bobbin case holder and having a needle clearing opening inits top, and a bobbin within said bobbin case; and a needle guard in theformo! a forwardly projecting cam edge at the periphery of the rotaryhook which passes behind the needle during descent of the latter withoutcontacting it normally, but which, in the event that the needle is bentor deflected, engages it before, it moves into the path ef the loopseizing beak of the rotary hook member to prevent it from fouling thebobbin within the bobbin case holder.

4. In a lockstitch sewing machine, a vertically reciprocating needle;cooperative complemental stitch-forming means including ahorizontallyarranged axially-hollow rotary hook component with a needleloop engaging beak and with an attached segmental gib providing a needleloop releasing tail, a frontally open non-rotating bobbin case holderwithin the hollow of the rotary hook component, a bobbin case fittingwithin said holder and having a needle clearing opening in its top, anda bobbin within said bobbin case; and a needle guard in the form of aforward edge cam projection on the gib aforesaid which passes behind theneedle during descent of the latter without contacting it normally, butwhich, in the event that the needle is bent or deflected, engages itbefore it moves into the path of the needle loop engaging beak toprevent it from fouling the bobbin within the bobbin case holder.

5. In a lockstitch sewing machine, a reciprocating needle; cooperativecomplemental stitchforming means including an axially-hollow rotary hookmember with an internal circumferential groove, a frontally opennon-rotating bobbin case holder having a narrower circumferential ribengaged in the groove of the rotary hook so that said bobbin case maynormally oat axially, a bobibn case tting within said holder and havinga needle clearing opening in its top, and a bobbin within said bobbincase; a steadying member adapted to coact with the bobbin case in urgingthe bobbin case holder inward of the rotary hook member to preventpinching of the needle thread between the rear face of the rib and thecorresponding face of the groove 'during each stitch-forming cycle; anda needle guard in the form of a forward cam projection at the peripheryof the rotary hook component which passes behind the needle duringdescent of the 30 latter without contacting it normally, but which, inthe event that the needle is bent or deflected. engages it to prevent itfrom fouling the bobbin within the bobbin case at times when the bobbincase holder is free to oat axially as aforesaid.

6. In a lockstitch sewing machine, a recipro cating needle; cooperativecomplemental stitchforming means having its axis at right angles to theneedle and including a rotating component with a. needle thread loopengaging beak; and a needle guard on and movable with said complementalstitch-forming means and arranged to engage the needlel before thelatter moves into the path of the loop engaging beak.

'1. In a lockstitch sewing machine, a reciprocating needle; cooperativecomplemental stitchforming means having its axis at right angles to theneedle and including a member with a needle lthread loop engaging beak;and a needle guard on said member radially beyond the beak arranged toengage the needle before the latter moves into the path of said beak.

CHARLES I". RUBEL.

